OTTAWA -- A judge has sentenced a Somalian man to 15 years in prison for the kidnapping of Amanda Lindhout, saying hostage-taking is a threat to the international community that deserves significant punishment.

Ali Omar Ader sat silently in the prisoner's box as Ontario Superior Court Justice Robert Smith handed down the sentence Monday.

It could be the final chapter in a nightmarish odyssey that began a decade ago in East Africa.

Smith ruled in December that Ader, 40, was a "willing participant" in the 2008 hostage-taking of Lindhout, who was working as a freelance journalist near Mogadishu at the time.

The judge found much of Ader's testimony unbelievable and did not support his claim that he was forced into serving as a negotiator and translator on behalf of a gang which threatened to harm him and his family.

Lindhout, raised in Red Deer, Alta., and photographer Nigel Brennan of Australia were snatched by armed men while pursuing a story, the beginning of a terrifying 15-month ordeal. They were released in November 2009 upon payment of a ransom.

The RCMP later lured Ader to Canada on the pretext of signing a lucrative book-publishing deal, leading to his arrest in Ottawa in June 2015.

Ader acknowledged to undercover officers that he had received $10,000 for his role in the kidnapping.

Although they testified at Ader's trial, neither Lindhout nor Brennan -- both severely scarred by events -- were present on Monday.

Ader's lawyers said at a March sentencing hearing that 10 to 12 years in prison would be appropriate. The Crown was seeking a term of 15 to 18 years.

In sentencing Ader to 15 years, Smith said he would receive six years' credit for time already spent in custody.

The "horrendous circumstances" of Lindhout and Brennan's confinement were an important factor in deciding the punishment, the judge said.

While Ader was not involved in physical or sexual assaults that Lindhout suffered, he was motivated by greed and did threaten to kill the hostages on several occasions if the ransom was not paid, Smith said.

Crown lawyer Xenia Proestos told reporters the sentence sends a strong message that Canada takes its international commitments very seriously, "and that we will pursue justice when these kinds of offences are committed against Canadian citizens anywhere in the world."

As negotiator for the gang, Ader held many long-distance telephone conversations with Lindhout's mother, Lorinda Stewart, who told him the family was selling possessions and scrambling to raise ransom money.

At one point Lindhout was driven at night into the desert, where a knife was held to her throat. While Ader was not present, he helped the gang connect a phone call to Stewart so she could hear her daughter's hysterical screams.

Delivering a prepared statement at the sentencing hearing, Lindhout said the confinement in squalid conditions left her with severe post-traumatic stress disorder, depression, the inability to sustain friendships, insomnia, nightmares, digestive problems and broken teeth.

"For years after my release I couldn't really believe I was free."

Brennan also read a victim impact statement, saying he, too, has suffered from post-traumatic stress, panic attacks and nightmares. Being forced to hear Lindhout's screams from torture in an adjoining room is "a memory that will mentally stay with me for the rest of my life," he said.

Ader expressed remorse at the March hearing, saying he was human and therefore flawed.

"I am sorry, I apologize and ask you for forgiveness," he said, requesting freedom so he could care for his family in Somalia.